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testo 550=zero out pressure sensors before every measurement.

Do you guys "zero out your pressure sensors before every
measurement" as the manual says. I don't see the purpose. The hoses just stay pressurised all the time. Lot of, I feel , unnecessary work, loose fittings, then tighten, (still a little refrigerent in hose) zero gauge ...
Thanks for any info

I bleed my hoses after every call and only zero out my gauges when they show above '1 lb' (instead of zero)... maybe every 2 weeks. You definitely DO want to check them from time-to-time. Especially if you are getting strange readings.

As the unit is digital you're zeroing out the electronics too. Battery condition, temperature, amount of vibration it was subjected to since last use and a host of other things can effect it's starting (power up zero) point. If you want accuracy I'd do it. If for no other reason than to take one more thing out of the list of possible reasons you might end up chasing your tail around looking for a ghost problem that doesn't exist. Just Sayin.

Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.